César TB, Manthey JA, Myung K
Journal of Natural Products, 2009
A new cyclic acetal (1) of marmin (6′,7′-dihydroxy-7-geranyloxycoumarin), two new cyclic acetals (5, 6) of 6′,7′-dihydroxybergamottin, and the known compounds marmin (2), 7-geranyloxycoumarin (3), bergamottin (4), and 6′,7′-dihydroxybergamottin (7) were isolated from grapefruit peel oil. All compounds were tested for inhibitory activity against intestinal cytochrome P450 3A4, an enzyme involved in the “grapefruit/drug” interactions in humans. Coumarins (1-3) exhibited negligible inhibitory activity, while the furanocoumarins (4-7) showed potent in vitro inhibitory activity with IC(50) values of 2.42, 0.13, 0.27, and 1.58 microM, respectively.
César TB, Manthey JA, Myung K. Minor Furanocoumarins and Coumarins in Grapefruit Peel Oil as Inhibitors of Human Cytochrome P450 3A4. J Nat Prod. 2009;72(9):1702-1704.